1. Field of the Invention
This invention relates to a method for separating hydrocarbons, and more precisely, a method for separating specifically determined hydrocarbons from other hydrocarbons as well as for separating the specified hydrocarbons into the respective structural isomers.
2. Description of the Prior Art
Aromatic hydrocarbons such as xylene, styrene, etc., olefins and some other kinds of condensed polycyclic hydrocarbons are extremely important in the field of petrochemical industries in these days as raw materials of synthetic resins, synthetic rubbers and other high molecular compounds and as raw materials of various kinds of derivatives, and these hydrocarbon substances are obtained from feed materials such as petroleum products, cracked gasolines, tar products, etc. for example by means of distillation or the like. For example, xylene is separated in general from petroleum reformates, etc. as mixed xylene by means of various kinds of distillation operations, and the thus obtained mixed xylene is further separated into the respective isomers by means of various methods and the thus separated isomers are collected. As the method for separating the mixed xylene into the respective isomers, various kinds of methods have been known, for example, fractional distillation, solvent extraction, adsorption chromatography, low-temperature processing, etc. However, all these methods require very complicated operations.
Olefinic hydrocarbons of four or more carbon atoms have various kinds of isomers, and these hydrocarbons are separated into the respective isomers by means of precision fractional distillation, extraction, extractive distillation, adsorption chromatography by molecular sieves, etc. Condensed polycyclic hydrocarbons are separated from tar products, petroleum products, etc. as raw materials by means of precision fractional distillation, extraction, crystallization, etc. after a light oil fraction has been distilled and separated. However, these methods require fairly complicated steps and the operation thereof also is fairly troublesome.
The inventors have studied the separation of hydrocarbons and as a result have found that a tri-halogenoacetate of a mono valent metal of group IB of the Periodic Table may form complexes with certain kinds of hydrocarbons, that the complex forming ability of the tri-halogenoacetate varies, depending upon the kinds of hydrocarbons, and that the formed complexes may easily be decomposed by means of water or heat to recover the hydrocarbons and the tri-halogenoacetate. On these grounds, the inventors have attained a new technical art to separate and purify various kinds of hydrocarbons by using the formation of complexes with the tri-halogenoacetate of a mono valent metal of group IB.